# How to convert or merge a tube into a single line curve?

i was only able to find posts about creating tubes from curves but found nothing about the reverse. converting mesh to curve will not work, it will give me a single circle of the cross section. Is it possible to automatically convert this into a single line curve? or even just a mesh with with single points merged at the center from each cross section edge.

if your curve has not to sharp curves, you can do this:

go to edit mode, ALT+S , scale down to "line", M -> merge by distance to get single vertices -> convert to curve

to change the spline type, just go to edit mode -> curve -> set spline type

• cool thats pretty awesome! thank you, is there also a way to convert (or decimate) the curve (or approximate) into a bezier curve? Mar 27, 2022 at 4:41
• just go to edit mode, then curve -> set spline type Mar 27, 2022 at 5:07
• thanks mate! i was thinking i could reduce the number of faces by converting my curve to bezier and then decimating it, turned out i gained more faces for my curve with depth XD Mar 27, 2022 at 13:50
• hi is this possible using geometry nodes? i have posted the question here blender.stackexchange.com/questions/259723/… Apr 6, 2022 at 7:48

I had to do this the other day, if your curve is more complicated than the great example given, this slightly different method works well.

In edge mode select all then alt deselect all the long edges so you just have the loops selected (or select edge rings if that works for you, depends on the mesh)

make sure you have individual origins selected

then just use standard S to scale down each ring

Once the ring size is less than the distance between each ring to merge by distance to make it single vertex

then you can do limited dissolve if you need to simplify it more and once happy do convert to curve

works great.

one other trick, if you enable the simplify curves addon that's included instead of decimating first you can use that to make a copy and force it to output bezier curves then you get a nice, optimised curve that easy to manage.

I usually do this:

1. In Edit mode switch to Edge select mode and manually select a single ring loop
2. Go to menu Select > Select Loops > Edge Rings (now you should have all ring loops selected)
3. Press M (or menu Mesh > Merge) > Collapse
4. Convert back to curve with Alt + C